Metal working processes, such as rolling, forging, casting, blanking, bending, drawing, ironing, cutting, punching, spinning, extruding, coining, hobbing, swagging embossing, cold heading and rolling, generally employ lubricants which are applied to the metal either before or during working. The lubricant reduces the friction between the metal and the machinery being employed in the particular metal working process. The reduction in friction results in reducing both the power required in performing the process and the wear of the surfaces of both the metal being worked and the metal working machinery. It also prevents adherence or sticking between the metal and the machinery and thus promotes processability by minimizing or eliminating disruption caused by such sticking.
After working, lubricant removal from the worked metal is frequently required, depending upon the use to which the metal is to be put. For example, if the metal is to be used in food packaging, such as cans, lubricant contact with the food may not be desirable, requiring lubricant removal to avoid flavor problems.
Heretofore, removal of many lubricants entailed the use of so-called washer chemicals. Washer chemicals are often expensive and may pose handling and/or disposal problems, consequently, their use is to be avoided where possible.
Another problem in metal working with lubricants resides in the form of the lubricant being applied. Liquid lubricants have limited load bearing capabilities and may be applied in films of limited thickness, thereby limiting the force that may be applied to the metal in any given forming or working step. This in turn may increase the number of forming steps required to complete a given forming operation which will increase the length of the process and require additional equipment, adding complexity and expense to the process.
Furthermore, liquid lubricants generally are more susceptible to attack by bacteria than solid lubricants and require the use of a biocide in their composition.
Some metal working processes use more than one lubricant and/or different concentrations or applications of the same lubricant in different stages of the process. For example, in making aluminum cans, liquid lubricant may be applied following the formation of sheet at one location or point in time. At a later point in time and likely at a different location, extrusion of the sheet will also require lubricant. Liquid lubricant applied following the sheet forming stage may have evaporated, flowed from the sheet or a part thereof or otherwise be wholly or partly removed requiring further lubricant application. This increases the cost of the process and adds a further step thereto.
The present invention is directed t overcoming one or more of the above problems and providing one or more of the above advantages.